| Prerequisites for checking cooling output of air conditioner |
| Vehicles with mechanically driven air conditioner compressor only, not for vehicles with a high-voltage system (hybrid vehicles) |
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| Ambient temperature above 15 ° C. |
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| Radiator and condenser clean; clean if necessary |
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| Poly V-belt for compressor drive OK and correctly tensioned, pulley actually driving air conditioner compressor (vehicles with a 4 or 6-cyl. engine) → Chapter. |
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| Air conditioner compressor drive unit correctly installed, air conditioner compressor actually being driven (vehicles with an 8-cyl. engine) → Chapter. |
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| All air ducts, covers and seals OK and properly installed. |
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| Air flow through dust and pollen filter not impeded by contamination → Chapter. |
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| Air intake (in fresh-air and air recirculation mode) not impeded by contamination or retrofitted components |
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| Vehicle not exposed to sunlight. |
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| Engine warm (coolant temperature above 80 °C) |
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| All dash panel vents open. |
| Following settings made on air conditioner operating and display unit, Climatronic control unit -J255- of „Basic“ type: |
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| „Auto“ mode (lamp in AUTO button lights). |
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| „Cold“ temperature setting (display „LO“ on Multi Media Interface display) |
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| Air conditioner compressor switched on (lamp in AC button lights). |
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| „Maximum speed“ pre-selected for fresh air blower (speed „10“ or higher indicated in Multi Media Interface display). |
| Following settings made on air conditioner operating and display unit, Climatronic control unit -J255- of „Deluxe“ type: |
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| „Auto“ mode (lamp in both AUTO buttons lights) |
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| „Cold“ temperature setting for driver and front passenger side (display „LO“ for driver and front passenger side on display of air conditioner operating and display unit and Multi Media Interface) |
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| Air conditioner compressor switched on (lamp in AC button lights). |
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| „Maximum speed“ pre-selected for fresh air blower (speed „10“ or higher indicated on display of air conditioner operating and display unit and Multi Media Interface) |
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| Lamp in AUTO button(s) goes out when the fresh air blower speed is altered manually. |
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| The maximum possible fresh air blower speed depends on various ambient influences (coolant temperature, vehicle electrical system voltage etc.). |
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| On vehicles with an air conditioner of the „Deluxe“ type, the potentiometer for rear temperature selection -G538- is set to „Cold“ (fitted in vent of rear centre console). |
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| On vehicles with an air conditioner of the „Deluxe“ type, the vent in the rear centre console is open. |
| Functions with engine running: |
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| Operation of radiator fan(s) (radiator fan -V7- and radiator fan 2 -V177-) (actuation and speed are governed by pressure in refrigerant circuit and engine temperature). |
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| Operation of fresh air blower -V2- at maximum speed (speed „10“ or higher) |
Note | The maximum possible fresh air blower speed depends on various ambient influences (coolant temperature, vehicle electrical system voltage etc.). |
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| Switching of the air conditioner to air recirculation mode (approx. 1 minute after starting the engine, the air flow/fresh-air flap is closed and the air recirculation flap opened, air is drawn in by the fresh air blower -V2- from the passenger compartment beneath the dash panel/behind the glove compartment). |
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